Is Tumblr now fertile ground for stealing ideas? Sierra Mist has a new ad—a cross promotion with The Office on NBC—showing a bunch of office workers flying toy helicopters around their workspace as Wagner's "Ride of the Valkyries" plays in the background. "Is your office this much fun?" the voice-over asks. The Sierra Mist spot is amazingly similar to a promo video that the young blog wizards at Tumblr released seven months ago. The same helicopters buzzing around the office; the same background music. Tumblr founder David Karp tells us he came up with the idea on a lark, to show off life in the office of the young company, and that the musical idea was "the result of being raised by a composer with an appreciation for theme music." He also tells us he wasn't contacted by Sierra Mist's ad agency before their ad went up. Scandal? We've emailed PepsiCo. for a response. It could be an uncredited rip off—or just a case of both being inspired by Apocalypse Now. Click to watch the clip above juxtaposing the two ads, and decide for yourself. [Full original Tumblr spot here. Full Sierra Mist ad here.]